Device at a boat

ABSTRACT

A device for switching between different operation modes of an electrical system on board a boat with an electric motor for propelling the boat comprises a control member ( 7 ) adapted to be actuated by hand for carrying out switchings in the electrical system between states corresponding to different operation positions thereof. A movable part ( 10 ) provided with first contact members ( 11 ) is movable with respect to a fixed part ( 9 ) with second contact members ( 13 ) belonging to the electrical system by moving the control member ( 7 ) by hand so as to enter into contact therewith and establish electric connections corresponding to different said operation positions of the electrical system.

FIELD OF THE INVENTION AND PRIOR ART

The present invention relates to a device for switching betweendifferent operation modes of an electrical system on board a boat withan electric motor for propelling the boat, in which the device comprisesa control member adapted to be actuated by hand for accomplishingswitchings in the electrical system between states corresponding todifferent operation positions thereof.

It may be a question of all possible types of boats, but the inventionis especially directed to smaller boats, and particularly, butaccordingly not exclusively, sailing boats provided with an auxiliarymotor, in which this advantageously is adapted to be able to operate asgenerator for loading batteries included in the electrical system whensailing.

A switching device of this type is used for obtaining differentoperation positions of the electrical system, which may correspond tofor example propelling or reversing of the boat through the motor or inthe case of a said charging possibility charging of said electricbatteries through the electric motor then driven in generator operation.Another operation position is a neutral position, in which the electricmotor is not driving the boat forwards or backwards and is neitherlocated in generator operation, and it is desired that in this operationposition no unnecessary electrical energy is consumed by the electricalsystem at the same time as a transition to operation including otheroperation positions of the electric motor may take place without anynoticeable delay.

The switching device in devices already known of this type has containedelectronic components for obtaining the switchings through acting upon acontrol member, such as a control slide. A pulse modulated speedregulator has then for instance been used. A disadvantage of a switchingdevice based on electronic components is that the operation thereof issensitive to using for example mobile telephones and other radiocommunication Furthermore, problems to cool the transistors included inthe electronic circuits also arise. Considering the environment in whichboats normally are present and the difficulties to rapidly get help atsea these switching devices already known are not as robust and reliableas desired.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a device of the typedefined in the introduction, which is simple to the construction, robustand functions with a high reliability under all conditions conceivableat sea.

This object is according to the invention obtained by providing such adevice with a movable part provided with first contact members andmovable with respect to a fixed part having second contact membersbelonging to the electrical system by moving the control member by handso as to enter into contact therewith and establish electric connectionscorresponding to different operation positions of the electrical system.

Thus, through the device according to the invention a switching betweenthe different operation positions is obtained in a purely mechanical waythrough a movement of a movable part with respect to a fixed part, whichmakes the device very simple. Accordingly, it is the position of themovable part with respect to the fixed part which through said contactmembers is directly decisive for which operation position the electricalsystem assume. The robustness and the operation reliability of such adevice get very high. Since no electronic components are included in theswitching device there is no risk of failure or heating thereof toomuch, so that it requires cooling.

According to a preferred embodiment of the invention one of said twoparts comprises a printed circuit card having conduction paths thereon,and portions of these conduction paths are adapted to form said contactmembers for co-operation with contact members on the other of the partsso as to establish said electric connections. It is advantageous thatthat part on which the printed circuit card is arranged is fixed and themovable part is provided with contact members in the form of contactpieces adapted to establish said electric connections between conductionpaths on the printed circuit card by bearing against the printed circuitcard, in which it is particularly advantageous if the device comprisesmembers storing potential energy and adapted to spring-loadedly presssaid contact pieces to bear against the printed circuit card, so thatthe contact pieces may bear continuously against and slide over theprinted circuit card when the movable part moves with respect to thefixed part. The different electric connections may by this be realizedin a very simple and at the same time reliable way for obtaining saiddifferent operation positions.

According to another preferred embodiment of the invention the movablepart may be pivoted with respect to the fixed part, which makes itpossible to use a lever as control member for easily moving between thedifferent relative positions of the fixed and the movable part.

According to another preferred embodiment of the invention the movablepart is adapted to be pivoted less than 180° with respect to the fixedpart, preferably between 100° and 60° with respect thereto for passingall possible said operation positions of the electrical system. Theelectrical system may by this through the device rapidly and comfortablybe brought between the different desired operation positions.

According to another preferred embodiment of the invention the contactpieces extend substantially radially and are adapted to mainly achieveelectric connections between conduction paths extending at a radialdistance to each other on the printed circuit card, which has turned outto be an advantageous way to obtain the different electricalconnections.

According to another preferred embodiment of the invention theelectrical system comprises one or more batteries adapted to deliverelectrical energy to said electric motor, and said electric connectionsare carried out to correspond to determined connection positions ofthese batteries with respect to the electric motor.

According to another preferred embodiment of the invention the devicecomprises means adapted to define distinct relative positions betweenthe movable and the fixed part corresponding to different steadyoperation positions of the electrical system, and according to anotherpreferred embodiment of the invention these steady operation positionsmay be one or more for propelling the boat through the electric motor,one or more for reversing the boat through the electric motor as well asa neutral position, in which the electric motor is not driven. In thecase that the electric motor of the electrical system is adapted to alsobe able to operate as generator and the electrical system also comprisesan arrangement for charging said batteries through the electric motor ingenerator operation, such an operation position may also be constitutedby a position for charging the batteries through the electric motor. Itis an advantage that there are such means for defining such distinctrelative positions, so that they may be obtained rapidly and exactly.The means may then for example be formed by members snapping into eachother in the respective relative position, so that the personcontrolling the control member clearly feels when the respectivedistinctive relative position is obtained.

According to another preferred embodiment of the invention said meansare adapted to define one steady operation position for high speedforwards and one for high speed backwards of the boat, and said contactmembers are adapted to establish electric connections in these positionsresulting in a series connection of batteries included in the electricalsystem for delivering a voltage to the electric motor formed by a sum ofthe voltages of such batteries, through which the motor may be suppliedwith energy for such high speed. Said means are in corresponding wayaccording to another preferred embodiment of the invention adapted todefine one steady operation position for normal speed forwards and onefor normal speed backwards of the boat, and the contact members areadapted to establish electric connections in these two operationpositions resulting in a parallel connection of batteries included inthe electrical system so as to deliver a voltage being just as high asthe voltage of an individual battery to the electric motor.

According to another preferred embodiment of the invention said meansare adapted to define one steady operation position in the form of aneutral position, in which the electric motor does not consume anyelectrical energy, and said contact members are adapted to establishelectrical connections in said neutral position so that the plus andminus pole of the electric motor are galvanically separated fromelectric batteries included in the electrical system. A neutral positionis by this obtained, in which the electric motor does not consume anyelectrical energy whatsoever from the electric batteries, so that thisposition may be assumed during long periods of time, at the same time asit constitutes a ready position, from which the movable part may rapidlybe moved with respect to the fixed part for assuming any other desiredoperation position whatsoever, for example propelling of the boat. Thus,the ability of the electrical system and the boat to react is increased,which is important when severe situations arise. It is very important torapidly obtain full traction power for stopping the boat, turning theboat against the wind, driving against a very heavy sea and wind andhandle other difficult situations. The invention enables this.

According to another preferred embodiment of the invention the contactmembers are adapted to establish electric connections corresponding toan operation position of the electrical system resulting in a smoothtransition to the respective operation position forwards or backwards ofthe boat by connecting said batteries to the electric motor through aresistor included in the device. The entire voltage of the batterieswill by this not suddenly come across the motor, which results in saidsmoother transition, while the control member thereafter may be movedinto a position, in which the resistor is disconnected for assuming thedesired operation position forwards or backwards of the boat.

The first contact members of the movable part are according to anotherpreferred embodiment of the invention adapted upon movement of themovable part with respect to the fixed part to slide along the fixedpart and successively establish electric connections corresponding to anumber of different operation positions. It is then advantageous if saidnumber of operation positions also comprises intermediate positionslocated between said steady operation positions, which the contactmembers are adapted to successively pass on their path between thesteady operation positions, which makes it possible to arrange suchintermediate positions and operation positions in such an order alongthe movement path of the movable part with respect to the fixed partthat an advantageous operation of the electrical system and primarily ofthe electric motor is obtained, and this forms also a furtheradvantageous embodiment of the invention in which the intermediatepositions are arranged in such a sequence and designed in such a waythat it is an advantage for obtaining one of said steady operationpositions that by before that passing operation positions of theelectrical system corresponding to preceding intermediate positions.

Further advantages as well as advantageous features of the inventionappear from the following description and the other dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

With reference to the appended drawings, below follows a specificdescription of a preferred embodiment of the invention cited as anexample.

In the drawings:

FIG. 1 is a schematic view, which very schematically illustrates thegeneral construction of an electrical system on board a boat, to which aswitching device according to the invention is applied,

FIG. 2 is a simplified view illustrating a part of the device accordingto the invention,

FIG. 3 is an elevation view of a movable part in the form of a turningplate of the switching device according to the invention according toFIG. 2,

FIG. 4 is an elevation view of a fixed part having a printed circuitcard of the device according to the invention according to FIG. 2, and

FIG. 5 is an enlarged, partially sectioned side elevation of the deviceaccording to the invention according to FIG. 2 arranged on a boat wall.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

The general construction of an electrical system on board a boat, towhich a switching device according to the present invention isapplicable, is illustrated in FIG. 1. The boat 1 is in this case asailing boat, which may be driven through wind power and/or electricallythrough an electric motor 2 included in the electrical system, whichhere is an electric direct current machine, preferably with a permanentmagnet motor. The electrical system has also electric batteries 3,preferably conventional 12 volts batteries, which are two to the number.These batteries are adapted to provide the electric motor withelectrical energy for driving an axle provided with a propeller 4 torotate for driving the boat forwards or backwards. The batteries arepreferably also adapted to supply refrigerator, autopilot and otherelectrical equipment on board the boat with electrical energy. However,as an alternative it is possible to have separate batteries for thissake.

The electric motor is advantageously also designed to be able to operateas generator for charging the batteries 3 with electrical energy througha charging arrangement 6 schematically indicated, when the boat issailed with a sufficiently high speed, normally at least three knots, soas to charge the batteries. The propeller 4 is for this sake preferablya so-called folding-propeller, so that the blades thereof may be foldedwhen no power transmission co-operation is desired between the water andthe propeller. Such a folding-propeller pivots the blades thereofoutwards by means of the centrifugal force in motor operation. Theblades are kept extended by the rotation obtained through the watermovement when sailing at charging. The only thing needed is to initiallyset the folding propeller into rotation by means of the motor. However,propellers having fixed blades are also conceivable.

A device for switching between different operation modes of theelectrical system has a control member in the form of a lever 7schematically indicated and which may be pivoted with respect to a wall8 of the boat on the place of the helmsman.

It will now be described how the switching device according to theinvention is constructed while making reference to the other FIGS. 2–5at the same time.

It is schematically illustrated in FIG. 2 how the two batteries 3 andthe electrical motor 2 are connected to a fixed part 9 of the switchingdevice. The switching device comprises also a movable part 10 in theform of a turnplate, which may be pivoted or turned with respect to thefixed part through actuation of the lever 7.

The turnplate 10 is shown in elevation in FIG. 3, and it appears thatthis has five first contact members 11 in the form of contact pieces ofelectrically conducting material extending substantially radially, whichare arranged with a mutual distance of 70–120°. It appears that two ofthem are arranged along the same radius on the turnplate. The contactpieces 11 are influenced by two springs 12 (see FIG. 5) in the directionout from the plane of the plate 10 and adapted to function as slidingcontacts. The turnplate 10 is also provided with two opposite slots 20defining end positions 21, 22 for the rotation of the turnplate by bolts23 projecting thereinto. It appears also that the turnplate is providedwith two spring loaded balls 24 intended to slide on the printed circuitcard and snap into recesses 25 (see FIG. 4) arranged therein so as todefine distinct relative positions between the printed circuit card andthe turnplate corresponding to different steady or permanent operationpositions of the electrical system.

The construction of the fixed part 9 is illustrated in FIG. 4 and thisis formed by a printed circuit card of an electrically insulatingmaterial, such as Bakelite or glass fibre with a high glass content.Conduction paths 13 of copper are arranged therein with a mutualdistance of about 2 mm, which is achieved by water cutting or millingout distance slots 26. More exactly, these conduction paths extend to alarge extent in the circumferential direction around an inner centrehole 14 of the fixed part. The contact pieces 11 are here schematicallyshown by dashing. Cables 27–32 are connected to the conduction paths andrun to the plus. (28, 29) and the minus pole (27, 32) and the electricalmotor (30, 31).

It appears in FIG. 5 that the fixed part 9 is intended to be fixed tothe rear side of a wall 8 of the boat, and that a bearing sleeve 15 isadapted to project through the centre hole 14. An axle 16 connected tothe lever 7 extends through the bearing sleeve and is through drivingdog brackets 17 rigidly connected to the turnplate 10, which is directedwith the contact pieces 11 thereof towards the conduction paths 13 ofthe printed circuit card. It also appears that an adjusting member inthe form of a set screw 18 is arranged for setting the bearing pressureof the turnplate 10 through the contact pieces 11 against the printedcircuit card 9 and at the same time function as driving dog of theturnplate 10.

Portions of the conduction paths 13 on the printed circuit card aredesigned to form second contact members for co-operation with thecontact members 11 on the turnplate in such a way that electricalconnections corresponding to different operation positions of theelectrical system mentioned above are obtained in different relativepositions of the turnplate 10 and the fixed part 9. The conduction paths13, of electrically conducting material, are designed in such a way thatin these different positions the batteries 3, the electric motor 2, aresistor 19 (see below), a charging arrangement 6 and possibly otherparts included in the electrical system are switched in different wayswith respect to each other.

It is in the present case a question of six such distinct relativepositions, which correspond in order in the path of movement of themovable part; high speed of the boat backwards, normal speed backwards,neutral position (see definition above), charging position (seedefinition above), normal speed forwards and high speed forwards.Furthermore, the contact pieces 11 and the conduction paths 3 aredesigned to co-operate in such a way that a number of differentoperation positions of the electrical system are obtained inintermediate positions located between said steady operation positionswhen the movable part is moved with respect to the fixed part and thecontact pieces 11 slide along the fixed part and successively establishelectric connections corresponding to the different operation positions.However, five distinct positions were well conceivable and are the mostnatural choice for a motor boat. Even four such positions may be there.

Furthermore, it is illustrated in FIG. 4 how the device has a resistor19 connected on the printed circuit card 9 between the conduction pathsthereof, said resistor being arranged so as to be switched in in serieswith the batteries in certain operation positions of the electricalsystem so as to obtain a smooth start of the electric motor forwards andbackwards, respectively, as well as smooth stopping the motor byconnecting the resistor between + and − on the motor. This resistor maywithstand power and may typically have a resistance of 0.25 ohm.

The contact pieces 11 and the conduction paths 13 are adapted to provideeighteen different electric connections corresponding to operationpositions of the electrical system with an extension of said movementpath over an angle of about 90° between two different end positions ofthe movement path of the turnplate with respect to the circuit card 9.These are in the present case in the order from one end positioncorresponding to high speed forwards to the other end positioncorresponding to high speed backwards the following, in which saiddistinct steady operation positions are underlined:

-   1. High speed forwards: the two batteries are connected in series,    which gives 24 volts direct voltage to the motor.-   2. High speed smooth start: the two batteries are connected in    series through a resistor 19 to the motor.-   3. Switching position: the two batteries are disconnected from each    other, no voltage to the motor. Through this position the mutual    connection of the batteries between series and parallel is changed.-   4. Normal speed. Smooth start: the two batteries are connected in    parallel through the resistor 19 to the motor.-   5. Normal speed forwards: the two batteries are connected in    parallel which gives 12 volts direct voltage to the motor.-   6. Normal speed. Smooth start: the two batteries are connected in    parallel and connected to the motor through the resistor 19.-   7. Protection position for charging: the two batteries are connected    in parallel, the plus pole of the motor is disconnected.-   8. The Propeller in charging position: the two batteries are    connected in parallel, the plus pole of the motor is connected to    the charging arrangement 6 and the minus pole of the motor to the    minus pole of the batteries.-   9. Protection position for charging: the two batteries are connected    in parallel and the plus pole of the motor is disconnected from the    battery.-   10. Smoothly braking: the two batteries are connected in parallel,    the plus pole of the motor is disconnected and the plus pole of the    motor and the minus pole of the motor are interconnected through the    resistor 19.-   11. Neutral position: the two batteries are connected in parallel,    the plus and minus pole of the motor are galvanically separated from    the batteries. A pole turning of the batteries with respect to the    motor so that plus gets minus and conversely is obtained through    this.-   12. Smoothly braking: the two batteries are connected in parallel,    the plus pole of the motor is disconnected and the plus pole of the    motor and the minus pole of the motor are interconnected through the    resistor 19.-   13. Normal speed: Smooth start: the two batteries are connected in    parallel and connected to the motor through the resistor 19.-   14. Normal speed backwards: the two batteries are connected in    parallel so as to give 12 volts to the motor.-   15. Normal speed. Smooth start: the two batteries are connected in    parallel through the resistor 19 to the motor.-   16. Switching position: the two batteries are disconnected from each    other, no voltage to the motor. The mutual connection of the    batteries between series and parallel is changed through this    position.-   17. High speed. Smooth start: the two batteries are connected in    series to the motor through the resistor 19.-   18. High speed backwards: the two batteries are connected in series,    which gives 24 volts direct voltage to the motor.

The different positions are arranged in such an order that it is anadvantage for obtaining one of said steady operation positions that theoperation positions of the electrical system corresponding tointermediate positions located therebefore have been passed. This meansthat it is an advantage at a transition for example from the positioncorresponding to normal speed forwards to the position corresponding tohigh speed forwards that the position 2 corresponding to high speedsmooth start has been passed. It is then for the best possible operationand obtaining a minimum wear of the parts advantageous if the controllever 7 is moved with a moderate movement speed, but the switchingdevice functions also excellent if the lever 7 is brutally pulled fromone position, for example high speed backwards to another position, inthe extreme case high speed forwards. When moving between the differentpositions these are so arranged with respect to each other thateverything has to take place in the correct order for a smooth functionof the electric motor, and a good timing between the switching in of thedifferent operation positions is obtained essentially independently ofhow fast the lever is moved. This is very important when the rotationdirection is changed “around” the neutral position.

A further advantage of the switching device according to the inventionis that it is possible starting from the neutral position, which doesnot consume any current, to very rapidly achieve full power forwards orbackwards, and that no extra button control is required before the motormay be started, but one may be located in this ready position withoutconsuming any extra energy for this sake. Also the charging position isa ready position. The control 7 may when needed rapidly be movedforwards or backwards and within some second full traction force in thedesired direction is obtained.

Another advantage is that the short circuit current is at smoothlybraking led through the resistor present for smooth start. The currentpeak generated at smoothly starting and smoothly braking is efficientlytaken care of by the resistor and the propeller, the axle clutch, themotor, the regulating device and the batteries are in this way saved.The smoothly braking is important when the direction of rotation ischanged, but also for braking a folding-propeller so that it is folded.Furthermore, it is advantageous that the motor is galvanically separatedfrom the battery in the neutral position for saving the sacrificialanode of the propeller and for reducing possibly galvanic corrosion onthe very motor. A switching device according to the invention can alsotake high currents, such as 500 A, with an extremely high (>99%)efficiency, and this is totally unelectronic. Another advantage is thatthe device according to the invention may be integrated with the 12V-system of the boat. Other consumers are connected to one battery. Thebatteries are besides shorter periods of time connected in parallel.Devices already known are preferably based on 24 V or 36 V, whichresults in problems for converting voltage, for example when charging inharbour.

The invention is of course not in any way restricted to the preferredembodiment described above, but many possibilities to modificationsthereof would be apparent to a person with skill in the art, without forthat sake deviating from the basic idea of the invention as defined inthe appended claims.

The invention could for example be applied to a regular motorboat andthe electrical system not provide any function of charging of batteriesthrough the electric motor, but such possibility to charging couldpossibly be provided in another way, such as through solar cells.

It would also be possible to arrange the conduction paths on the movablepart, even if it is probably to prefer that they, especially consideringthe cable connections thereto, are arranged on the fixed part.

The batteries could have a rated voltage of 6 V or 24 V instead, so thatthen 6 or 12 V and 24 or 48 V, respectively, could be delivered to themotor instead for 12 or 24 V.

If the motor and especially the batteries are placed far away from thehelmsman's place it may be advantageous to place the control, deviceclose to the batteries or the motor for reducing the voltage drop andweight. 1 m cable has a weight of about 0.5 kg and we have here sixcables. An extra lever may then instead be placed at the helmsman'splace for controlling the switching device through a control wireconnected thereto.

1. A device for switching between different operation modes of anelectrical system on board a boat (1) with an electric motor (2) forpropelling the boat, in which the device comprises a control member (7)structured and arranged to be actuated by hand for accomplishingswitchings in the electrical system between states corresponding todifferent operation positions thereof, and comprises a movable part (10)provided with first contact members (11) and pivotal with respect to afixed part (9) having second contact members (13) belonging to theelectrical system by moving the control member by hand to enter intocontact therewith and establish electrical connections corresponding todifferent operation positions of the electrical system, one of said twoparts comprises a printed circuit card (9) having conduction paths (13)thereon, portions of the conduction paths being structured and arrangedto form said contact members for co-operation with contact members (11)on the other of the parts to establish said electric connections, andthe other of the parts being provided with contact members in the formof contact pieces (11) structured and arranged to establish saidelectric connections between conduction paths (13) on the printedcircuit card by bearing against the printed circuit card, and comprisingmeans (12) for storing potential energy and structured and arranged tospring-loadedly press said contact pieces (11) to bear against theprinted circuit card (9).
 2. A device according to claim 1,characterized in that the control member is formed by a lever (7)connected to the movable part (10) and structured and arranged to bepivoted with respect to the fixed part (9) for switching betweendifferent operation positions.
 3. A device according to claim 1,characterized in that the movable part (10) is structured and arrangedto be pivoted less than 180° with respect to the fixed part (9) forpassing all possible operation positions of the electrical system.
 4. Adevice according to claim 1, characterized in that the conduction paths(13) are arranged on the fixed part (9).
 5. A device according to claim1, characterized in that said contact pieces (11) extend substantiallyradially and are arranged to mainly establish electric connectionsbetween conduction paths (13) extending at a radial distance to eachother on the printed circuit card.
 6. A device according to claim 1,characterized in that the electrical system comprises one or morebatteries (3) arranged to deliver electrical energy to said electricmotor (2), and said electric connections are carried out to correspondto determined connection positions of these batteries with respect tothe electric motor.
 7. A device according to claim 6, in which theelectric motor (2) of the electrical system is structured to alsofunction as a generator and the electrical system also comprises anarrangement (6) for charging said batteries through the electric motorin generator operation, and the contact members (11, 13) are structuredand arranged to establish electric connections enabling a function ofcharging the batteries through the electric motor.
 8. A device accordingto claim 6, characterized in that it is structured and arranged forswitching between different operation modes of an electrical systemprovided with batteries (3) of low voltage type having a rated voltageof 6, 12, or 24 V, preferably 12 V.
 9. A device according to claim 1,characterized in that it comprises means (24, 25) structured andarranged to define distinct relative positions between the movable (10)and the fixed (9) part corresponding to different steady operationpositions of the electrical system.
 10. A device according to claim 9,characterized in that said means are structured and arranged to defineat least three said steady operation positions, namely one forpropelling the boat through the electric motor (2), one for reversingthe boat through the electric motor and one neutral position, in whichthe electric motor is not driven.
 11. A device for switching betweendifferent operation modes of an electrical system on board a boat (1)with an electric motor (2) for propelling the boat, in which the devicecomprises a control member (7) structured and arranged to be actuated byhand for accomplishing switchings in the electrical system betweenstates corresponding to different operation positions thereof,characterized in that it comprises a movable part (10) provided withfirst contact members (11) and movable with respect to a fixed part (9)having second contact members (13) belonging to the electrical system bymoving the control member by hand to enter into contact therewith andestablish electrical connections corresponding to different operationpositions of the electrical system and means (24, 25) structured andarranged to define distinct relative positions between the movable (10)and the fixed (9) part corresponding to different steady operationpositions of the electrical system, wherein said means are structuredand arranged to define at least six steady operation positions, andthese are one for high speed forwards and one for high speed backwardsof the boat through the electric motor, one for normal speeds forwardsand one for normal speed backwards of the boat through the electricmotor, said neutral position and a position for charging said batteries(3) when the electric motor (2) operates as a generator.
 12. A deviceaccording to claim 9, characterized in that said means are structuredand arranged to define a steady operation position for high speedforwards and one for high speed backwards of the boat, and said contactmembers are structured and arranged to establish electric connections inthese positions resulting in a series connection of batteries (3)included in the electrical system for delivering a voltage to theelectric motor (2) formed by the sum of the voltages of such batteries.13. A device according to claim 9, characterized in that said means arestructured and arranged to define a steady operation position for normalspeed forwards and one for normal speed backwards of the boat, and thecontact members are structured and arranged to establish electricconnections in these two operation positions resulting in a parallelconnection of batteries (3) included in the electrical system to delivera voltage being just as high as the voltage of an individual battery tothe electric motor (2).
 14. A device according to claim 9, characterizedin that said means are structured and arranged to define a steadyoperation position in the form of a neutral position, in which theelectric motor (2) does not consume any electrical energy, and saidcontact members are structured and arranged to establish electricalconnections in said neutral position so that the plus and minus pole ofthe electric motor are galvanically separated from the electricbatteries (3) included in the electrical system.
 15. A device accordingto claim 14, characterized in that said contact members are structuredand arranged to form electric connections in the neutral positionresulting in a parallel connection of batteries (3) included in theelectrical system.
 16. A device according to claim 9, characterized inthat said means are structured and arranged to define one steadyoperation position for charging the batteries (3) included in theelectrical system through the electric motor (2) then being in generatoroperation, and said contact members are in said charging positionstructured and arranged to establish said electric connectionscorresponding to a connection of a plus pole of the motor to thecharging arrangement and a minus pole of the motor to a minus pole of abattery as well as a parallel connection of batteries included in theelectrical system.
 17. A device according to claim 10, characterized inthat the contact members are structured and arranged to establishelectric connections corresponding to an operation position of theelectrical system resulting in a smooth transition to the respectiveoperation position forwards or backwards of the boat by connecting saidbatteries (3) to the electric motor (2) through a resistor (19) includedin the device.
 18. A device according to claim 1, characterized in thatsaid contact members are structured and arranged to establish anoperation position corresponding to smooth braking of the electric motorby connection batteries (3) included in the electrical system inparallel to each other, disconnecting the plus pole of the electricmotor (2) from the batteries and interconnecting the plus and minus poleof the motor through a resistor (19).
 19. A device according to claim 1,characterized in that the first contact members (11) of the movable part(10) are upon movement of the movable part with respect to the fixedpart (9) structured and arranged to slide along the fixed part andsuccessively establish electrical connections corresponding to a numberof different operation positions.
 20. A device according to claim 9,characterized in that said number of operation positions also comprisesintermediate positions located between said steady operation positions,and the first contact members (11) are structured and arranged tosuccessively pass these positions on their path between the steadyoperation positions.
 21. A device according to claim 18, characterizedin that the intermediate positions are arranged in such an order andstructured and arranged in such a way that it is an advantage forobtaining one of said steady operation positions to before that passoperation positions of the electrical system corresponding to precedingintermediate positions.
 22. A device according to claim 3, characterizedin that the movable part (10) is pivotal between 100° and 60° withrespect to the fixed part (9) for passing all possible operationpositions of the electrical system.
 23. A device for switching betweendifferent operation modes of an electrical system on board a boat (1)with an electric motor (2) for propelling the boat, in which the devicecomprises a control member (7) structured and arranged to be actuated byhand for accomplishing switchings in the electrical system betweenstates corresponding to different operation positions thereof, andcomprises a movable part (10) provided with first contact members (11)and movable with respect to a fixed part (9) having second contactmembers (13) belonging to the electrical system by moving the controlmember by hand to enter into contact therewith and establish electricalconnections corresponding to different operation positions of theelectrical system, and the movable part (10) is a turnplate mounted uponan axle (16) to which the control member (7) is attached.